There has been considerable interest in methods for the Quantitation of Catecholamines in biological specimens. It is now clear that catecholamine neurotransmitters have been implicated in connection with schizophrenia, depressive suicides, behavioral changes as well as a number of the affective disorders. The most frequently employed technique for the determination of catecholamines is fluorescence. Unfortunately the sensitivity and selectivity from the methodology often is not sufficient for routine clinical use. Recently High Pressure Liquid Chromatography with a Amperometric electrochemical detector has become widely used. This detector uses a very small glassy carbon electrode which converts only a small fraction of the electroactive species which is separated by the chromatography column. We will attach a coulometric detector to the High Pressure Liquid Chromatograph. Coulometric detectors have certain advantages that should help increase sensitivity and reduce the influence of electrode contamination on the sensitivity. Since the electrode reactions for catecholamines are understood, quantitation becomes easier since peak area reflects the number of electrons transferred in the redox reaction.